The present invention relates, in general, to a computer integrated manufacturing (CIM), and, more particularly, to a production management system and method which are suitable for process management in the production process for mounting parts on a substrate such as a printed substrate or a ceramic substrate.
There have so far been attempts of automation in individual manufacturing units which are arranged in the process of manufacturing products such as printed substrates or the like on which many kinds of parts are mounted by small quantities like a CPU, a memory, various kinds of interfaces, controllers, etc. for use in computers and various kinds of control apparatuses. These manufacturing units, however, are managed individually independent of each other and no special consideration has been given to the management of positioning of individual processes of manufacturing the products in the production schedule, tuning of one manufacturing process with other processes, tuning of the state of producing one product with that of other products which are to be placed in the same manufacturing process, etc., which have all been managed manually.
Under this situation, there has been proposed a system which integrally manages production processes for manufacturing many kinds of products in small quantities.
This system is applied to the processes of producing printed substrates, and has a management structure which is divided into high, medium and small orders of management. In this structure of the management system, the high system manages the overall functions of a plant such as an order-making management, a design management, a parts management, etc., the medium order system manages manufacturing lines including managements or receiving of data from a high order(upper), supply of data to a low order(lower), and a progress management, and the low order system receives manufacturing information from the low order system and controls various automation equipments installed in the production lines.
The above-described conventional management system has a hierarchical structure to thereby generally manage various automatic devices provided in the manufacturing processes from the high order in accordance with the production schedule. It is considered that, by such arrangement, it is intended that the production management as described above is systematized and automated.
The above-described conventional management system is featured in that the high order system and the low order system exchange information through the medium order system.
This conventional management system, however, is considered to have the following problems.
A first problem is that a heavy burden is applied to the medium order system because all the information exchanges are performed through the medium order system. For example, when there is a large quantity of data to be transmitted from the high order system to the low order system or when there are frequent accesses to the medium order system, the medium order system becomes busy, having a potential of causing a bottleneck in the access to the medium order system, which will make it difficult to manage the whole system in real time.
In other words, this kind of problem will occur very easily since usually a large quantity of data is included in the manufacturing information such as numerical control (NC) data which is required in each automatic equipment. Further, since all the low order systems are connected to the low order systems through the medium order systems, each low order system asks the medium order systems for data pertaining to other processes required whenever it becomes necessary, so that the frequency of making access to the medium order systems increases, having a high risk of inviting the above problem.
A second problem is that since all the low order systems are connected to the high order systems through the medium order systems, there may occur such a situation that the low order systems cannot obtain data required and accordingly the manufacturing must be interrupted, when a part of the equipments is in fault, particularly when the medium order systems are down. This becomes a serious problem because the occurrence of this situation affects the system as a whole.